#include <stdio.h>

int mystrlen(char *arr)
{
	int i=0;
	while(arr[i]!='\0')
	{
		i++;
	}

	return i;
}

char * mystrcat(char *arr1,char *arr2)
{
	int num1=mystrlen(arr1);
	int num2=mystrlen(arr2);
	for(int i=0;i<num2;i++)
	{
		arr1[num1]=arr2[i];
		num1++;
	}
}

int main(int argc, const char *argv[])
{	
	char arr1[20]="nihao";
	char *arr2="niyehao";
	mystrcat(arr1,arr2);
	printf("%s\n",arr1);
	
	return 0;
}
